#include<iostream>
#include<algorithm>
#include <vector>
#include<cmath>
#include<iomanip>
#include<queue>
using namespace std;
typedef long long int lint;
/*vector<char>al(26);
al = { 'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z' };*/
/*vector<char>AL(26);
AL = { 'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z' };*/
int main() {
	vector<char>al(26);
	al = { 'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z' };

	int cnt = 0;
	string S;
	cin >> S;
	int Z = S.size();
	if (Z % 2 == 0) {
		cout << "No" << endl;
	}
	else {
		for (int ia = 0; ia <= (Z - 1) / 2-1; ia++) {
			for (int ib = 0; ib < 26; ib++) {
				if (S.at(ia * 2) == al.at(ib)) {
					cnt++;
				}
			}
			if (S.at(ia * 2 + 1) == ' ') {
				cnt++;
			}
		}
		for (int ic = 0; ic < 26; ic++) {
			if (S.at(Z - 1) == al.at(ic)) {
				cnt++;
			}
		}
		if (cnt == Z) {
			cout << "Yes" << endl;
		}
		else {
			cout << "No" << endl;
		}
	}
}